Typical milling machines have what is termed a quill in which an end mill, drill, etc. is held and rotatably driven by a drive motor. The quill is vertically movable towards and away from a workpiece. A quill handle is normally attached to a spindle or shaft that, when rotated, moves the quill towards and away from the workpiece.
A prior "speed handle" allows an operator to quickly reposition the handle with respect to the shaft. Due to the gearing between the shaft and the quill, several rotations of the handle may be needed to move the quill between its extreme positions. However, during actual use, the quill is normally moved vertically, only a short distance, i.e., to drill a shallow bore. In the prior handle assembly, a reciprocatably movable pin is operatively connected to a handle forming part of the assembly. The handle assembly is maintained to the quill shaft by a set screw that loosely engages a groove formed in the shaft. The engagement between the screw and the groove enables the handle assembly to rotate relative to the quill while remaining engaged to the quill shaft. The single pin under the control of the handle engages a selected one of a plurality of bores forming part of the quill, thereby locking the handle to the quill to prevent relative rotation when the handle member is in an engagement position. This type of handle enables an operator to reposition the handle so that it is in a desired position (where maximum mechanical leverage can be obtained by the operator) for the particular machining operation.
With this prior "speed handle", excessive operator force could shear the single pin. If the pin fails, the handle assembly becomes useless. Additionally, the prior "speed handle" can be complicated and expensive to manufacture. In order to mount the pin to the handle member, a rather complicated slot is formed centrally in the handle member and is adapted to receive the head of the pin. This slot requires precise and costly machining.